Electromagnetic voltage regulator



May 12, 1959 B. K. NASTER ELECTROMAGNETIC VOLTAGE REGULATOR 2 Sheets-Sheet 1 Filed Nov. 21, 1957 OUT INVENTOR. ber'f K. Nas'rer (dawn/41d,

A1 Tor-men s vof the regulator.

United States Patent ELECTROMAGNETIC VOLTAGE REGULATOR Bert K. Naster, Hollywood, Fla.

Application November 21, 1957, Serial No. 698,012

7 Claims. (Cl. 32345) This invention relates to a voltage regulator, adapted to supply substantially constant output voltage over a wide range of input voltage.

One object of the present invention is to provide a new and improved voltage regulator utilizing electro-magnetic elements and maintaining a high degree of regulation over a wide range of input voltages.

A further object is to provide a new and improved voltage regulator of the foregoing type which achieves a degree of regulation far exceeding that achieved with prior magnetic regulators, and comparing very well with the regulation achieved with the best electronic regulators.

Another object is to provide a voltage regulator which is extremely rugged and compact, yet is reasonably easy to manufacture and low in cost.

Further objects and advantages of the present invention will appear from the following description, taken With the accompanying drawing, in which:

Fig. 1 is a schematic wiring diagram of a voltage regulatorsto be described as an illustrative embodiment of the present invention.

Fig. 2 is a somewhat pictorial wiring diagram of the regulator, showing the general layout ofthe magnetic cores and coils.

Fig. 3 is a somewhat simplified circuit diagram of the regulator.

.Fig. 4 is a plan view of one of the transformers employed in the regulator.

v Fig. 5 is a cross-sectional view, taken generally along the line 5-5 in Fig. 4.

Figs. 613 are vector diagrams illustrating the operation "As already indicated, Figs. 1-3 illustrate a regulator 10 adapted to furnish a substantially constant output voltage at a pair of output terminals 12 and 14, even though the input voltage'supplied to the regulator may vary 1 over a considerable range. to a pair of input terminals 16 and 18. In the arrange- The input voltage is applied ment of Figsl and 2, the input terminals 16 and 18 take theform of the prongs of a plug 20, adapted to be inserted into an ordinary household electrical receptacle. 1 Similarly the output terminals 12 and 14 are formed on a receptacle 22, into which an appliance or the like may 'be'plugged.

1 The input will often be alternating current from an ordinary household power line supplying approximately 115 volts at 50 cycles.

The regulator has many applications. Thus, it may In the home,

From Figs. 1 and 2, it will be apparent that the reg- However, the regulator may be made to operate at any, desired input voltage and frequency. The regulator will often be arranged to supply a regulated output voltage of 115 volts, but it may be 1 made to supply any desired output voltage.

5 manner.

2 ,886,767 Patented May 12, 1959 ice ulator 10 comprises first and second transformers 24 and 26. As illustrated to best advantage in Figs. 2 and 4, the first transformer 24 has a magnetic core 28, which may be made up of a stack of iron laminatons, in the usual The core 28 may be arranged in various ways, but the illustrated core is provided with an elongated central leg 30 which extends longitudinally across an elongated rectangular ring 32. Saturable butt joints 34 and 36 are provided between the central leg 30 and the ring 32 at the opposite ends of the central leg.

The first transformer 24 has a first primary coil P1 which is mounted on the central leg 30 adjacent one end thereof. In addition, the first transformer 24 has first, second and third secondary coils S1, S2, and S3, all of which are mounted on the central leg 30. It will be seen that the first secondary coil S1 is mounted at the extreme right-hand end of the central leg 30, immediately adjacent the primary coil P1. The second and third secondary coils S2 and S3 are on the opposite end of the primary coil, with the second coil S2 disposed between the primary coil P1 and the third coil S3.

In order to give the second secondary coil S2 a high degree of leakage reactance, magnetic shunts 38 are provided on the core 28 between the primary coil P1 and the secondary coil S2. In this case, the shunts 38 take the form of projections which extend inwardly from the ring 32 into closely spaced relation to the central leg 30.

Similarly, magnetic shunts 40 are intenposed between the Second and third secondary coils S2 and S3, to give the third coil S3 an extremely high degree of leakage reactance. It will be realized that both the shunts 38 and 40 are between the primary coil P1 and the third secondary coil S3. The shunts 40 are somewhat wider than the shunts 38 and, thus, have a greater magnetic mounted on the central leg 44 at the opposite ends thereof. Magnetic shunts 52 are interposed between the secondary coil S4 and the primary coil P2, to give the secondary coil a high degree of leakage reactance.

The circuit arrangement of the primary and secondary coils is subject to numerous variations. In the illustrated arrangement, however, the first and second primary coils P1 and P2 of the first and second transformers 24 and 26 are connected in series between the input terminals 16 and 18. The input circuit between the terminals 16 and 18 may be traced along a lead 54, the first primary coil P1, a lead 56, the second primary coil P2, and a lead 58. The secondary S4 on the second transformer 26 is arranged to feed power into the primary P1 on the first transformer 24. In this case, the secondary S4 is connected directly across the first primary coil P1.

In the illustrated arrangement, the second output terminal 14 is connected directly to the second input terminal 18, by means of a lead 60 which is connected to the lead 58. The first input terminal 16 is connected to the first output terminal 12 by a series circuit that may be traced through the lead 54, the first primary coil P1, the first secondary coil S1, a lead 62, the third secondary coil S3, and a lead 64. It will be observed that the first secondary coil S1 is connected to the junction between the first and second primary coils P1 and P2.

The regulator 10 is provided with a capacitive feed back circuit, which comprises a capacitor C1. In this case,

the capacitive feed back circuit is connected between the junction lead 62 and the first input terminal 16. The feed back circuit comprises the second secondary coil .52 and the capacitor C1 in series. It will be noted that the capacitive feed back circuit is connected to the junction between the secondary coils S1 and S3. The current in the feed back circuit results from the voltages across the first primary coil P1 and the first secondary coil S1, as well as the voltage across the second secondary coil S2. The output current through the third secondary S3 also has an effect on the current through the feed back capacitor C1.

To improve the regulation and the waveform of the output voltage a second capacitor C2 is connected across the terminals 12 and 14.

Various other refinements of the circuit are shown in Figs. 1 and 2. Thus, a fuse 66 and a switch 68 may be connected in series with the lead 54. A pilot lamp 70 may be mounted across the input leads 54 and 58. In this case, the lamp 743 is of the neon type, with a current limiting resistor 72 in series therewith. A voltmeter 74 may also be connected between the leads 54 and 58, to indicate the input voltage. Similarly, a second voltmeter 76 may be connected between the output terminals 12 and 14 to indicate the output voltage.

In the arrangement of Fig. 1, the primary coils P1 and P2 and the secondary coils S1 and S4 are provided with tap switches 78, 80, 82, and 84 to adjust the output voltage and compensate for Variations in the output load. These tap switches constitute a refinement which is not strictly necessary, particularly when the output load is constant and the desired output voltage is known. It

' will be seen that the tap switch 78 is adapted to switch secondary S4.

The tap switch 80 is adapted to switch the input lead 58 between any of a plurality of taps 90 at the end of the secondary primary coil P2. In this way, the effective number of turns in the coil P2 is changed slightly.

The tap switch 82 is similarly adapted to switch the lead 62 to any of a plurality of taps 92 at one end of the first secondary coil S1. This changes the effective number of turns in the coil S1.

In like manner, the tap switch 84 is connected to various taps-94 at one end of the coil S4, so as to change the effective number of turns in the coil.

In Fig. 2, arrows have been drawn on the various coils to indicate the direction of winding. While the construction of the coils may be varied to a considerable extent, it may be helpful to present detailed information with respect to one actual model which has been employed Qoil Number of Operating Current turns Voltage (Amp.)

It was observed that the voltages across S4 and P2 were about 110 degrees out of phase with each other. The voltages across P1 and S1 were 180 degrees out of phase.

For this test, the value of the first capacitor C1 was 7 4 microfarads, while the value of the second capacitor C2 was 4.75 microfarads.

It has been found that the regulator maintains nearly constant output voltage over'an extremely wide range of input voltage. The performance of the regulator is outstanding; not only with respect to the degree of regulation achieved, but also with regard to the extremely wide range of input voltage that maybe accommodated. The excellent regulation achieved by the regulator is demonstrated by the following table, which shows the results of an actual test in which the output voltage was observed as the input voltage was varied over a wide range.

Input voltage: Regulated output voltage Itis somewhat difficult to-give a concise explanation as to how the, regulator operates to provide a substantially constant output voltage as the input voltage is varied. However, the regulation is believed to be due to several factors. One factor is the manner in which the second transformer 26 feeds power back into the first transformer 24, by Way of the secondary S4. Another factor is thought to be the manner inwhich the first capacitor feeds leading current back to the input terminal from the coils P1, S1, and S2. Still another factor is the high leakage reactance of the secondary coils S2, S3, and S4. Moreover,'there is also the variable reluctance provided by the saturable joints 34, 36, 48 and at the ends of the central legs on the transformers.

It is believed that a condition of resonance or near resonance exists in the capacitive feed back circuit. This is evident from the high voltages across the capacitor C1 and the secondary S2. These high voltages indicate that the capacitive reactance of the capacitor and the inductive reactance of the coil S2 are largely cancelling each other so as to permit the flow of a relativelylarge current through the feedback capacitor.

The resonance condition in the capacitor circuit is illustrated in the vector diagrams of Figs. 6-13. These diagrams are based in part on the fact that the output voltage is the vector sum of the input voltage plus the voltages across C1, S2, and S3. Figs. 9-13 illustrate this vector addition for several different values of input voltage. In

these diagrams, the input voltage is designated V while the output voltage is designated V The voltages across C1, S2, and S3 are designated Vet, V and V It will be seen from Figs. 9-13 that the vector representing the sum of the voltages across C1, S2, and S3 increases with increasing'input voltage. Actually, this vector increases somewhat more rapidly than the increasing voltage. The vector rotates in angular position as the input voltage is increased, so as to maintain the output voltage substantially constant.

The vector diagrams of Figs. 6, 7, and 8 are drawn to account for the rotation and rapid increase of the vector representing the sum of the voltages across C1, S2, and S3. These diagrams are based on the observation that the last mentioned vector is the sum of the vectors representing the voltage across C1 and the sum of the voltages across S2 and S3. The diagrams of Figs. 6, 7, and 8 are for successively increasing input voltages of 100, and volts. It will be observed that boththe vector V and the vector V plus V increase with increasing input voltage, but the increase ofV is somewhat more rapid,

with the result that the vector V plus V plus V rofor prior magnetic regulators. The degree of regulation compares very well with the best electronic regulators. It has been found that the regulating action is very rapid,

with the result that the output voltage is completely stabilized within two or three cycles of the alternating current, after any change in the input voltage.

The regulator is of great value for use with military, industrialand laboratory equipment requiring constant input voltage. It is also advantageous for use with a television set, to prevent variations in line voltage from affecting the picture. When the regulator is thus employed, the line voltage may change a great amount without any perceptible change or unsteadiness in the picture.

The regulator has another surprising and highly advantageous feature, in that the output terminals may be short circuited without damaging the regulator or causing excessive current in the input or the output circuit. It is thought that this result may be attributed to the high leakage reactance of the secondary S3. Because of this feature, the regulator is immune to damage due to accidental short circuits across the output terminals. Moreover, the regulator restores .the outputvoltage as soon as the short circuit is removed.

Since the regulator employs magnetic components, it is extremely durable and compact, yet is reasonably low in cost. There are no moving parts or electric components to get out of order.

Various modifications, alternative constructions and equivalents may be employed without departing from the true spirit and scope of the invention, as exemplified in the foregoing description, and defined in the following claims.

I claim:

1. In a voltage regulator, the combination comprising a first transformer having a first primary coil and first, second, and third secondary coils, said first transformer having a magnetic core with said coils mounted thereon, said first secondary coil being mounted on said core adjacent said primary coil, said second secondary coil being mounted on said core with a first magnetic shunt disposed between said primary coil and said second secondary coil, said third secondary coil being disposed on said core with a second magnetic shunt between said second and third secondary coils, a second transformer having a second magnetic core with a second primary coil and a fourth secondary coil mounted thereon, said second core having a third magnetic shunt between said second primary coil and said fourth secondary coil, first and second input terminals, a primary circuit connecting said first and second primary coils in series across said input terminals, means connecting said fourth secondary coil across said first primary coil to feed back power into the same, said primary circuit being arranged with said first input terminal connected to said first primary coil and with said second input terminal connected to said second primary coil, first and second output terminals with said second output terminal connected directly to said second input terminal, an output circuit connecting said first and third secondary coils in series between said first output terminal and the junction of said first and second primary coils, a capacitive feed back circuit comprising a first capacitor connecting in series with said second secondary coil between said first input terminal and the junction between said first and third secondary coils, and a second capacitor connected across said output terminals.

2. In a voltage regulator, the combination comprising a first transformer having a first primary coil and first, second, and third secondary coils, said first transformer 6 having a magnetic core with said coils mounted thereon, said first secondary coil being mounted on said core adjacent said primary coil, said second secondary coil being mounted on said core with a'first magnetic shunt disposed between said primary coil and said second secondary coil, said third secondary coil being disposed on said core with a second magnetic shunt between said second and third secondary coils, a second transformer having a second magnetic core with a second primary coil and a fourth secondary coil mounted thereon, said second core having a third magnetic shunt between said second primary coil and said fourth secondary coil, first and second input terminals, a primary circuit connecting said first and second primary coils in series across said input terminals, means connecting said fourth secondary coil across said first primary coil to feed back power into the same, said primary circuit being arranged with said first input terminal connected to said first primary coil and with said second input terminal connected to said second primary coil, first and second output terminals,- an output circuit connecting said first and third secondary coils and said output terminals in series between said second input terminal and the junction of said first and second primary coils, and a capacitive feed back circuit comprising a first capacitor connecting in series with said second secondary coil between said first input terminal and the junction between said first and third secondary coils.

3. In a voltage regulator, the combination comprising a first magnetic core with a first primary coil and a plurality of secondary coils thereon, magnetic shunt means between said first primary coil and at least some of said secondary coils, a second transformer having a second magnetic core with a second primary coil and an additional secondary coil thereon, additional magnetic shunt means between said second primary coil and said additional secondary coil, first and second input terminals connected respectively to said first and second primary coils, a primary circuit connecting said primary coils in series between said input terminals, means connecting said additional secondary coil to said first primary coil to feed back power into the same, first and second output terminals with said second output terminal connected directly to said second input terminal, an output circuit connected between said first output terminal and the junction of said first and second primary coils and including at least one of said secondary coils of said first transformer, and a capacitive feed back circuit connected between said output circuit and said first input terminal and including a capacitor connected in series with at least another of said secondary coils of said first transformer.

4. In a voltage regulator, the combination comprising a first magnetic core with a first primary coil and a plurality of secondary coils thereon, a second transformer having a second magnetic core with a second primary coil and an additional secondary coil thereon, first and second input terminals connected respectively to said first and second primary coils, a primary circuit connecting said primary coils in series between said input terminals, means connecting said additional secondary coil to said first primary coil to feed back power into the same, first and second output terminals, an output circuit connected in series with said output terminals between said second input terminal and the junction of said first and second primary coils and including at least one of said secondary coils of said first transformer, and a capacitive feed back circuit connected between said output circuit and said first input terminal and including a capacitor connected in series with at least another of said secondary coils of said first transformer.

5. In a voltage regulator, the combination comprising a first transformer having a magnetic core with a first primary coil and first, second and third secondary coils thereon, said first core having magnetic shunt means imparting high leakage reactance to said second and third secondary coils, a secondtransformer having a magnetic core with ,a second primary coil and a fourth secondary coil thereon, magnetic shunt means on said sec ond core imparting high leakage reactance to said fourth secondary coil, first and second input terminals connected respectively to said first and second primary coils, a primary circuit connecting said primary coils in series between said input terminals, means connecting said fourth secondary coil across said first primary coil, first and second output terminals with said second output terminal connected to said second input terminal, a capacitive feed back circuit including a capacitor connected in series with said first and second secondary coils and said first primary coil, and a circuit connecting said third secondary coil between said first output terminal and the junction of said first and second secondary coils.

6. In a voltage regulator, the combination comprising a first transformer having a magnetic core with a first primary coil and first, second and third secondary coils thereon, a second transformer having a magnetic core with a second primary coil and a fourth secondary coil thereon, first and second input terminals connected respectively to said first and second primary coils, a primary circuit connecting said primary coils in series between said input terminals, means connecting said fourth secondary coil across said first primary coil, a capacitive feed back circuit including a capacitor connected in series with said first and second secondary coils and said first primary coil, first and second output terminals, and a circuit connecting said third secondary coil and output terminals'in series betweensaid second input terminal and the junction of said first and second secondary coils.

7. In a voltage regulator, the combination comprising a first transformer having a magnetic core with a first primary coil and first, second and third secondary coils thereon, said first core having means imparting high leakage reactance to said second and third secondary coils, a second transformer having a magnetic core with a second primary coiland a fourth secondary coil thereon, means on said second core imparting high leakage reactance to said fourth secondary coil, first and second input terminals connected respectively to said first and second coils, a primary circuit connecting said primary coils in series between said input terminals, means connecting said fourth secondary coil across said first primary coil, first and second output terminals with said second output terminal connected to said second input terminal, a capacitive feed back circuit including a capacitor connected in series with said first and second secondary coils and said first primary coil, first and second output terminals, and a circuit connecting said third secondary coil and output terminals in series between said second input terminal and the junction of said first and second secondary coils.

No references cited.

Patent No. 2,886,767 May 12, 1959 Bert K. Naster It is hereby certified that error of the above numbered patent requiring Patent should read as corrected below.

appears in the printed specification correction and that the said Letters Column 1, line 61, for "50 cycles" read 60 cycles Signed and sealed this 15th day of September 1959.

SEAL) Attest:

KARL H, AXLINE ROBERT C. WATSON Attesting Officer Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Bert K, Naster It is hereby certified that error of the above numbered patent requiring Patent should read as corrected below.

appears in the printed specification correction and that the said Letters Column 1, line 61, for "50 cyeles" read n 60 cycles Signed and sealed this 15th day of September 1959::

(SEAL) Attest:

KARL HB AXLINE ROBERT C. WATSON Attesting Ofiicer Commissioner of Patents 

